Trapeziometacarpal (i.e. carpometacarpal or CMC) arthritis of the thumb

The thumb carpometacarpal (CMC) joint is an irregularly shaped, biconcave saddle joint that allows for complex movements including circumduction, opposition, pinch, grasp, and fine manipulation. Biomechanical studies have shown that when the thumb is under load, the deep anterior oblique ligament and the dorsal radial ligament prevent radial subluxation². If the joint becomes hypermobile, stress may lead to cartilage breakdown and degeneration of the articular surfaces³. The degeneration begins on the palmar aspect of the joint, with radiographic prevalence in about 7% of men and 15% of women above 50 years old^4,5. Risk factors for CMC joint degeneration predominantly include female sex, hypermobility, increased body mass index, post-traumatic (e.g., Bennett fracture), and Ehlers-Danlos syndrome. Some patients may remain asymptomatic, while others develop pain, weakness, and instability that can severely limit hand function. Patients often complain of pain with pinch grip or opposition. Concomitant carpal tunnel syndrome (CTS) and de Quervain’s tenosynovitis may be present in up to 43% and 15% of patients, respec tively, which can confound the patient’s clinical RSWP presentation⁴.

On physical exam, there can be thumb base promi nence with progressive ligamentous incompetence of the anterior oblique and dorsal radial ligaments. The thumb metacarpal may subluxate dorsally and proximally, thereby leaving the distal portion in adduction toward the palm. Compensatory metacarpophalangeal (MP) hyper extension to allow for an increased first web space leads to a characteristic “z-deformity” that can be appreciated both clinically and radiographically. Tenderness is typically located at the radial thumb CMC joint with radiation to the palmar thenar region. Varus and valgus stress might elicit pain in a hypermobile joint. Special clinical tests include the traction-shift (i.e., subluxation-relocation) test and the axially loading grind test. The traction shift test has greater sensitivity and specificity than the axially loading grind test (67% and 100% versus 30% and 97%, respectively). The traction shift test is performed by the examiner applying longitudinal traction to the thumb with dorsal pressure over the base of the metacarpal⁶. A subluxated joint will reduce, thereby eliciting pain. The axially loading grind test is performed by applying axial compression to the thumb while moving the thumb into flexion, extension, and circumduction. Pain indicates a positive test. Of note, excessive flexion could mimic Finkelstein’s test and initiate pain in patients with concomitant de Quervain’s tenosynovitis, which is felt more proximal to the joint but can certainly overlap⁷.

Radiographs assess severity based on the Eaton-Littler classification system⁸. True anteroposterior (AP), lateral, and Robert’s view radiographs may initially demonstrate widening at the CMC joint with minimal subluxation⁹. Progression to a narrowed CMC joint with further sub luxation, osteophytes, sclerosis, and subchondral cysts are indicative of more severe arthritis. Involvement of the adjacent scapho-trapeziotrapezoidal (STT) joint re ceives the highest grade of severity, as can be found in 64% of thumb CMC arthritis cases. Notably, concomitant STT arthritis can be a source of residual pain following trapeziectomy¹⁰. Stress radiographs may be useful to elicit CMC joint instability and early CMC joint arthritis^3,11. Although radiographic changes can be significantly advanced, it should be emphasized that radiographic severity doesn’t necessarily correlate with the degree of clinical symptoms. It is important to recognize that some patients with advanced radiographic changes of CMC arthritis may be minimally asymptomatic, while other pa tients with mild radiographic changes could present with significant clinical pain¹².

Non-operative management begins with rest, non-steroidal anti-inflammatory drugs (NSAIDs), and splinting to decrease mechanical stress and inflammation. Usually, patients with unstable or hypermobile thumb CMC joints are good candidates for splinting. The splint should posi tion the thumb in palmar abduction with slight flexion and medial rotation¹³. Two main CMC splint types are used to immobilize the thumb MP joint: (1) a long opponens that extends past the wrist and (2) a short opponens that is hand-based. Another option, a Colditz splint, im mobilizes the CMC but not the MP joint. Overall, each provide similar pain relief outcomes^14,15. Corticosteroid injections (CSI) to the CMC joint are often beneficial in the short-term, although these are potentially more use ful as a diagnostic tool than for long-term treatment^4,13. Additionally, there is evidence that pain and grip strength can improve when patients are educated on thumb rest with activity modification¹³.

Surgical treatment most commonly consists of trape ziectomy, either alone or combined with ligament recon struction and/or tendon interposition (LRTI). There is little evidence of method superiority, as many methods are associated with good success⁷. CMC joint arthroscopy is a relatively new field and therefore lacks substantive data to support treatment applicability¹¹. Isolated volar ligament reconstruction may be an option for early disease, but this method only addresses the hyperlaxity of the joint without improving pain from joint degeneration. Arthrodesis is a rarely performed option for heavy laborers who present with moderate CMC disease and absence of concomitant STT arthritis. The desired fusion position places the thumb in 30-40 degrees of palmar abduction, 10-20 degrees of radial abduction, and 15 degrees of pronation to allow for key pinch¹¹. Pyrocarbon arthroplasty implants have recently been developed, but there is insufficient data to demonstrate their effectiveness at this time, given higher complication and reoperation rates¹⁶.

Scaphotrapeziotrapezoid arthritis (STT)

STT arthritis is the third most common arthritis affecting the wrist10. It can occur in isolation but most commonly occurs with basilar thumb arthritis or a scapholunate advanced collapse (SLAC) wrist. While the etiology is unknown, the development of STT arthritis may be related to carpal mechanics associated with a form of non-dissociative dorsal intercalated segmental instability^10,17. Isolated STT arthritis may be associated with “idiopathic” scapholunate dissociation, pseudogout, CTS, flexor carpi radialis (FCR) tendonitis, and de Quervain’s tenosynovitis¹⁸.

Pain with radial deviation can indicate STT arthritis or radiocarpal arthritis. Swelling may be present in the region of the STT joint, and sharp pain may be elicited with range of motion at the thumb or wrist. Onset is usually insidious and progressive with loss of grip strength. On exam, the practitioner can expect pain with the radial grind test where the wrist is radially deviated to load the STT joint¹⁹. Thumb CMC arthritis can have concomitant STT arthritis and is recognized as a source of residual pain after a successful trapeziectomy¹⁰. Radiographs have a lower accuracy for detecting STT arthritis compared to intra-operative evalu ation¹⁰. Nonetheless, standard three-view radiographs of the thumb are useful in demonstrating narrowing between the scaphoid and trapezium or trapezoid, the presence of osteophytes, or calcium deposition in the triangular fibrocartilage complex region indicative of pseudogout as a source of pain¹⁸.

Initial conservative treatment consists of activity modification, rest, NSAIDs, splinting, and CSIs. Injections have not been studied specifically for STT arthritis²⁰. The majority of hand surgeons treat isolated STT arthritis by trapeziectomy with LRTI, but some choose arthrodesis and few favor distal scaphoid resection¹⁰. Triscaphe fu sions have shown fair patient satisfaction but may lead to nonunion, loss of wrist ranges of motion, and need for future surgery with ongoing pain related to progressive arthrosis of the radiocarpal and thumb CMC joints²⁰. Distal scaphoid resection is a less frequently utilized option due to the concern that it can lead to further destabilization of the mid-carpus. Advantages, however, include the ease of procedure, limited immobilization, and potentially faster recovery¹⁹.

Wrist osteoarthritis (OA)

Wrist OA is often traced back to a traumatic insult such as a fracture, dislocation, or ligamentous injury¹⁷. A SLAC wrist is one of the most common patterns of wrist arthritis in adult patients. Degenerative changes occur due to articular malalignment and abnormal mechanics of the scaphoid, lunate, and distal radius with deficiency of the scapholunate ligament. Arthritis first occurs between the radial styloid and the scaphoid, then progresses to the more proximal radioscaphoid articulation, and finally in volves the capitolunate joint while sparing the radiolunate joint¹⁵. Alternatively, an untreated scaphoid nonunion following a prior scaphoid fracture may lead to another predictable pattern of carpal instability termed scaphoid nonunion advanced collapse (SNAC)²¹. The degenera tive changes are similar to a SLAC wrist with one notable difference - the proximal pole/fracture fragment of the scaphoid that remains attached to the scapholunate liga ment is usually spared from developing arthritic changes. Other causes of wrist OA include malunion or articular joint incongruency from a prior distal radius fracture, crystal arthropathies, avascular necrosis of the lunate or scaphoid (Kienböck and Preiser disease, respectively), and congenital abnormalities²².

Symptoms can include generalized pain, stiffness, and a sense of instability. Notably, evidence of radiographic wrist arthritis does not necessarily correlate to symptom severity²³. Clinical assessment is therefore of paramount importance²². Consideration should be given to how symptoms are affecting the patient’s work and lifestyle. A thorough evaluation of the primary wrist joints should include the radioscaphoid and radiolunate joints as well as the capitolunate joint at the capitate head. Secondary joints to evaluate include the STT, ulnolunate, and distal radioulnar joints²⁴. Meticulous evaluation of posteroante rior (PA) and lateral radiographs of the wrist should ac company a physical exam to determine if the location of pain correlates to radiographic abnormality. Additionally, obtaining a bilateral clenched fist view of both wrists on the same radiograph can offer an excellent comparison view when assessing SLAC/SNAC wrist and can facilitate recognition of a prior scapholunate injury.

Non-surgical treatment revolves around symptom al leviation with immobilization, rest, activity modification, NSAIDs, and CSIs¹⁷. Surgical treatment may include de nervation by neurectomy, debridement by styloidectomy, arthroplasty, or partial/total wrist arthrodesis. It is critical to discuss how surgery can involve a significant investment by the patient due to prolonged immobilization and time away from work with the potential for loss of motion that may be more burdensome than the original symptoms²². Neurectomy can help with pain while preserving wrist range of motion and should be considered if the patient has pain relief after an injection of anesthetic around the anterior interosseous nerve (AIN) and/or the posterior interosseous nerve (PIN)¹⁷. Radial styloidectomy can be performed when arthritis is confined to the radial styloid, although the extent of resection must be limited. If more than 6 to 10 mm of the styloid is resected, the radioscapho capitate and radiolunotriquetral ligaments can be severely compromised, thereby leading to carpal instability²⁵.

Proximal row carpectomy (PRC) involves removal of the scaphoid, lunate, and triquetrum. This surgery is a viable option for radioscaphoid arthritis in the setting of healthy appearing proximal capitate and preserved lunate fossa cartilage of the distal radius. After removal of the proximal row of the carpus, the distal carpus migrates proximally and articulates in the lunate fossa to function as a simple hinge joint. Due to an inherent size mismatch of the novel articulation, arthritis may subsequently form at this joint¹⁷. PRC remains a good option for younger patients due to a shortened period of immobilization post-operatively. Additionally, PRC preserves the range of motion through the creation of a neo-articulation be tween the capitate and the lunate fossa. Studies have shown that at 10-year follow-up, the average wrist range of motion following PRC was approximately 63% of the contralateral wrist²⁶. Four corner fusion involves removal of the scaphoid and fusion of the lunate, capitate, triquetrum, and hamate. The procedure is performed when arthritis has progressed to involve the midcarpal capitolunate joint and can only be done in the setting of a healthy radiolunate joint. It can be a salvage procedure for advanced arthritis while still preserving grip strength and range of motion to about 50-60% of the contralateral wrist^27-29.

In advanced arthritis with involvement of the lunate fossa, where the above surgical options are not possible, wrist arthrodesis or arthroplasty may be the only options. Arthroplasty is more often reserved for patients with rheumatoid arthritis due to severe limitations of postoperative weight bearing and activity²⁴. It can also be useful for patients with bilateral wrist arthritis, in which one side undergoes wrist fusion and the other side undergoes wrist arthroplasty, in order to preserve unilateral wrist range of motion on the arthroplasty side for activities of daily living²⁴. Arthrodesis of the radiocarpal joint, usually achieved by a dorsal spanning plate, exchanges range of motion for pain relief.¹⁷ Fusion limits range of motion to about 30-40% of the contralateral wrist, but modification including excision of the distal pole of the scaphoid may increase range of motion by up to 25%.³⁰.

Scaphoid fracture

Scaphoid fractures usually result from a fall on an out stretched hand with the wrist in extension and radial de viation. Despite comprising 50-70% of all carpal fractures, acute scaphoid fractures can often go unrecognized or be misdiagnosed as a wrist “sprain.” Practitioners should therefore have a high suspicion of scaphoid fracture in the setting of pain in the anatomic snuffbox (Fig. 1). Concomitant injuries may include distal radius fracture or peri-lunate injuries with associated carpal fractures. Anatomically, 80% of the scaphoid is covered with car tilage, and blood flow enters distally at the level of the dorsal ridge. This retrograde blood supply renders more proximal fractures vulnerable to vascular insufficiency and increases the risk for nonunion³¹.

Patients typically present with radial wrist pain and a story consistent with the aforementioned mechanism. They demonstrate tenderness to palpation over the anatomic snuffbox and/or scaphoid tubercle with pain elicited from axial compression to the thumb³². Radiographs include four views: PA, scaphoid view, lateral, and 45 degrees semi-pronated oblique³³. In the acute setting, about 15% to 35% of scaphoid fractures can be missed with initial radiographs^34,35. Traditionally, patients with physical exam findings suggestive of scaphoid injury, but with negative radiographs, should be immobilized in a thumb spica splint or cast with the return to clinic in two weeks for repeat imaging. Resorption at the fracture site may lead to a more visible fracture line on repeat, delayed imaging. However, more recent studies have suggested that advanced imag ing is more cost-effective given the cumulative cost of cast immobilization, return clinic visits, repeat radiographs, and potentially lost wages while in a cast³⁶. Deciding between MRI and CT scan in this acute setting is less clear. MRI has increased sensitivity (88%) and specificity (100%) for detecting edema patterns consistent with acute, non displaced fractures but comes at a much greater cost³⁷. CT scans, although having decreased sensitivity (72%) and specificity (99%), are faster and generally easier to obtain in the emergency room setting, but these come with increased radiation burden^33,37. Ultrasound, despite being less expensive, has not been proven as a reliable secondary imaging test for detecting scaphoid fracture, as it is highly dependent on the operator and is complex to perform. Displacement assessment has been shown to be superior with the adjunct of a CT as compared to radiographs alone³⁸.

Conservative management for nondisplaced scaph oid waist or distal pole fractures often consists of cast immobilization for at least eight weeks³⁹. With regard to immobilization, Clay et al showed no difference in union rate between a short arm cast with or without thumb in terphalangeal joint immobilization⁴⁰. Historically, operative treatment was reserved for displaced fractures or fractures prone to nonunion. Interestingly, systematic review and meta-analysis of acute nondisplaced or minimally dis placed scaphoid waist fracture management showed that percutaneous fixation had union rates comparable with those of cast immobilization but with faster return to work and faster time to union (2.5 months versus 1.5 months) without significant difference in complication rates⁴¹. Therefore, proceeding with operative versus nonoperative management of acute nondisplaced scaphoid fractures is variable depending on patient factors and surgeon preference. Clearer indications for surgical intervention of acute fractures include proximal pole fractures, displaced fractures regardless of anatomic location, and fractures with concomitant injuries. Fixation is routinely achieved with compression screws, although it may occasionally be performed or supplemented with Kirschner wire fixation in the case of small fragments²⁵.

If a patient presents with either a missed scaphoid frac ture or with a nonunion following attempted nonoperative and occasionally operative treatment, surgery is typically performed with the use of bone graft. Non-vascularized bone graft can be used when the proximal fracture frag ment remains viable, and vascularized bone graft is instead used when the proximal fragment demonstrates evidence of avascular necrosis. Another novel salvage able option is scaphoid proximal pole excision and recon struction with the hamate’s proximal pole, which allows harvesting on the same surgical field and the use of the capitohamate ligament to repair the scapholunate liga ment⁴². Preoperative evaluation of viability of the scaphoid fragment can be assessed with MRI⁴³. Surgical treatment aims to avoid a SNAC wrist, as described above.

Scapholunate ligament (SLL or SL) Injuries

The SLL is a three-part ligamentous structure, strongest dorsally, that stabilizes wrist carpal kinematics. Ligamen tous injury can lead to carpal instability and subsequent development of wrist arthrosis that first manifests along the radial aspect of the radiocarpal joint leading to RSWP. The diagnosis of SLL insufficiency classically relied on static radiographic measurements, but this failed to capture pa tients with dynamic scapholunate interval widening when the wrist was mechanically loaded⁴⁴. It is now known that insufficiency can manifest as both static and/or dynamic instability depending on the severity and chronicity of ligament injury⁴⁴.

The injury typically occurs with a fall onto a hyperex tended, ulnarly deviated, and supinated wrist. There can be diffuse swelling about the wrist without localized tender ness. Patients with subacute injuries will have more local ized tenderness to the dorsal SL interval, decreased grip strength, and often a painful popping/clicking sensation with activities. Specialized tests to evaluate for scapholu nate ligament insufficiency include the scaphoid shift test (i.e. Watson test) and the finger extension test. The scaph oid shift test is performed by the examiner placing their thumb on the scaphoid tubercle and their fingers around the distal radius (Fig. 1). The thumb pushes a dorsally-directed force on the scaphoid with counterpressure from the fingers. The examiner’s other hand then moves the patient’s hand from a position of ulnar deviation/extension to radial deviation/flexion while maintaining direct thumb pressure on the scaphoid tubercle. This maneuver serves to dorsally subluxate the scaphoid base from its natural position. Thumb pressure is then released causing the scaphoid base to return to its native position in the scaph oid facet of the distal radius, oftentimes with a clunking sensation. A positive test occurs when this maneuver is painful. Due to ligamentous laxity, the scaphoid shift test may be falsely positive in up to one-third of patients⁴⁴. The finger extension test can be performed by placing the patient’s wrist in flexion and having the examiner resist active finger extension. A positive test occurs when this maneuver causes discomfort in the wrist.

Appropriate radiographs to evaluate for SLL injury in clude PA, lateral, scaphoid view, and a bilateral clenched fist view focusing on the SL interval with both wrists on the same radiograph for better comparison. On the PA view, widening of the SL interval greater than 3 mm, also known as the “Terry Thomas sign” when widening is extreme, is suggestive of SLL insufficiency, although it should be noted that there is normal anatomic variation in ligamen tous laxity and any obvious widening should be compared to the contralateral side for a baseline⁴⁴. Additional signs of SLL insufficiency can include the “signet ring sign” in which the abnormally flexed scaphoid demonstrates overlapping of the distal pole and scaphoid waist with the resultant appearance of a radiographic ring. There can also be foreshortening of the scaphoid on the PA film when the scaphoid is excessively flexed more than 70 degrees. The lateral radiograph should be repeated if the radius, capitate, and long finger metacarpal are not collinear in the sagittal plane, as this orientation represents a true lateral of the carpus⁴⁴. A scapholunate angle greater 70 degrees is considered highly suggestive of increased flexion of the scaphoid⁴⁴. In addition, the lateral radiograph can show dorsal intercalated segment instability (DISI) with dorsal tilt of the lunate and progressive dorsal subluxation of the capitate on the lunate. The bilateral clenched fist view is best for evaluating dynamic instability⁴⁵. 3-T MRI has been found to have a specificity of 89.8-99.6% and a sensitivity of 66.8-83.2% for diagnosing SL ligament tears. Sensitivity can be improved with an MR arthrogram to 76.1-87.2%^46,47.

SLL injuries are categorized into various descriptive groups that are useful in determining the appropriate treat ment: (1) occult instability (i.e. no discernible SL widening) with a partially intact ligament, (2) dynamic instability (i.e. SL widening on stress views) with a repairable ligament, (3) reducible SL dissociation without a repairable ligament, (4) reducible DISI deformity without associated arthritis, and (5) DISI deformity with associated arthritis or SLAC wrist^44,48. Depending on the degree and chronicity of SLL injury, as well as the presence or absence of associated arthritic changes, treatment options will vary⁴⁹. Treatment of a partially torn SLL can consist of immobilization or wrist arthroscopy with debridement, thermal shrinkage, and/or percutaneous pinning⁵⁰. If a repairable ligament is present, then direct repair should be achieved. For groups 3 and 4 where the ligament is irreparable, bone-ligament-bone grafts or other ligament reconstruction techniques can be utilized. For group 5, treatment often consists of PRC or scaphoidectomy with midcarpal arthrodesis in the form of four-corner fusion (lunate, capitate, hamate, triquetrum), although other variations of midcarpal fusion exist⁴⁹.

De Quervain’s tenosynovitis

De Quervain’s, or first dorsal compartment tenosynovitis, is thought to be due to repetitive motion between the tendons of abductor pollicis longus (APL) and extensor pollicis brevis (EPB) that produces a fibroblastic response with swelling and tenosynovium thickening⁵¹. Rather than demonstrating inflammatory changes, histology shows thickening of the tendons and retinaculum, increased vascularity, and accumulation of mucopolysaccharides that may lead to mucoid degeneration. De Quervain’s typically affects adults in the fifth and sixth decade, but it is also common in peripartum and lactating women⁵². In this latter population, the disease is usually self-limiting and resolves after conservative management.

Gradual onset of pain occurs along the radial styloid with the potential for radiation proximally to the forearm or distally to the thumb (Fig. 1). It can be exacerbated by grip, thumb abduction, and wrist ulnar deviation. Diagnosis is made based on physical exam. Routine radiographs or advanced imaging is not necessary unless ruling out other painful sources such as thumb CMC and/or STT arthritis, which can certainly coexist. Specifically, Finkelstein test, Eichhoff test, and the Wrist Hyperflexion and Abduction Test (WHAT) are suggestive of de Quervain’s pathology. Finkelstein test is performed by the examiner grasping the thumb and ulnarly deviating the wrist⁵³. Eichhoff test, com monly confused with Finkelstein, involves the examiner ulnarly deviating the wrist while the thumb is clasped in the palm. WHAT has a higher sensitivity and specificity than Eichhoff’s test (99% and 29% versus 89% and 14%, respectively) and is performed by the patient hyperflexing the wrist and abducting a thumb in full interphalangeal (IP) and metacarpophalangeal (MP) extension against a resistive force⁵⁴.

Conservative management consists of rest, splint ing, NSAIDs, and corticosteroid injections (CSIs). The CSI is performed overlying the radial styloid with the needle parallel to the first dorsal compartment. It has been determined that complete relief can be achieved in 80% of patients⁵⁵. Immobilization after CSI increases cost, inhibits activities of daily living, and does not contribute to improvement in relation to CSI alone⁵⁶. In the peripartum and lactating population, Avci et al. compared the efficacy of CSI versus splinting. Although limited by sample size, CSI provided complete relief of symptoms while splinting did not⁵². When nonsurgical management fails, open surgical release of the first dorsal compartment with identification of sub-compart ments and protection of the radial sensory nerve can be performed with good results. Up to 60% of patients with de Quervain’s can have a septum between the APL and EPB tendons, which needs to be released during surgery for optimal symptom relief⁵⁷.

Intersection syndrome

Patients with intersection syndrome typically complain of pain roughly 4 cm proximal to the radial styloid, a more proximal location than pain in de Quervain’s tenosynovi tis, due to friction at the site of intersection between the first (i.e. APL and EPB tendons) and second (i.e. wrist extensor tendons) dorsal compartments (Fig. 1)⁵⁸. Pa tients may also experience swelling and crepitation with wrist extension and flexion. Pain is exacerbated by wrist motion, especially resisted extension. There is a higher incidence of intersection syndrome in men compared to de Quervain’s tenosynovitis⁵⁹. Ultrasound may be helpful to distinguish intersection syndrome from de Quervain’s tenosynovitis, although it is a diagnosis primarily based on physical exam⁵⁹.

Non-operative treatment with splinting at roughly 15 degrees of wrist extension, NSAIDs, avoidance of exac erbating activities, and CSI can provide complete relief. If ongoing pain, surgical release often reveals swelling within the first compartment muscle bellies and tenosynovitis of the second compartment tendons. Symptom relief has been accomplished with decompression of the second dorsal compartment without intervening on the first dorsal compartment⁵⁸.

Extensor pollicis longus (EPL) tenosynovitis

EPL tenosynovitis is rare, especially in patients without rheumatoid arthritis. Anatomically, the EPL takes a sharp turn at Lister’s tubercle, which can lead to in creased friction with motion. Tenosynovitis can occur in the setting of repetitive motion such as in drummers or following nonoperative treatment of nondisplaced distal radius fractures⁶⁰. Microangiographic studies postulated that increased pressure within the tendon sheath of these nondisplaced fractures jeopardizes the blood flow to an already poorly vascularized ten don, thereby increasing the risk for degeneration and possible rupture ⁶¹. Another postulated mechanism for tenosynovitis is direct injury to the EPL tendon during a fall with impaction of the tendon between Lister’s tubercle and the base of the third metacarpal⁶². The EPL tendon can also become irritated in the setting of a volar distal radius plate with prominent screws along the far cortex of the dorsal distal radius⁶³.

Patients can present with diffuse wrist pain or with more focal symptoms of pain and swelling localized to Lister’s tubercle⁶⁴. Pain may be exacerbated by active or passive thumb extension. Patients may also present with trigger ing, snapping, or crepitus over the EPL tendon due to a size mismatch with the third dorsal compartment⁶⁰. In this case, it is important to perform a good physical exam to distinguish between flexor pollicis longus (FPL) triggering volarly and thumb EPL triggering dorsally. Recognition of EPL tenosynovitis is important, as progressive degenera tion of the tendon can lead to tendon rupture with inability to extend the thumb at the IP joint. The diagnosis does not necessitate imaging, but both ultrasound and MRI can be used to further evaluate for EPL tenosynovitis when the diagnosis is unclear. It is argued that ultrasound is superior due to the oblique course of EPL tendon, which makes it difficult to visualize on MRI⁶⁵. Furthermore, the dynamic nature of ultrasound can be beneficial in documenting triggering or snapping.

Surgery is the preferred method of treatment due to high risk of EPL tendon rupture with chronic attrition^60,66. The extensor retinaculum over the third dorsal compart ment is released followed by sectioning of the adjacent septae between the second and fourth compartments. While some argue that bowstringing occurs if the tendon is not included under the extensor retinaculum, studies have demonstrated that transposition of the EPL superficial to the extensor retinaculum is a safe and effective method of treatment⁶⁴.

Stenosing tenosynovitis of the flexor pollicis longus (FPL)

Although stenosing tenosynovitis of the flexor tendons most commonly affects the ring and long fingers, the thumb is the third most commonly affected digit⁶⁷. Associated factors are as follows: female sex, hand sports, repetitive trauma (e.g., manual work), diabetes mellitus, rheumatoid arthritis, hypothyroidism, CTS, calcific or septic tendinitis, crystal arthropathy, amy loidosis⁶⁶. Regarding the thumb, the FPL approaches the palmar plate at a more acute angle than the digital flexor tendons before entering the retinacular tunnel. This anatomic configuration may contribute to the higher frequency of triggering in the thumb⁶⁸. Inflammation leads to thickening of the tendon or tendon sheath that can occur focally or more diffusely. If localized, the inflammation is usually just distal to the A1 pulley caus ing deformation and development of a palpable nodule known as a “Notta’s nodule”. The diffuse pattern may have inflammation that extends beyond the A1 pulley. The resultant pathological disproportion between the volume of the retinacular sheath and its contents leads to dysfunction of tendon gliding.

Pain is typically located overlying the volar base of the thumb metacarpophalangeal joint at the A1 pulley in the region of the Notta’s nodule, but patients may pres ent with radiating pain more proximally to the radial wrist or more distally to the thumb (Fig. 1). They may note clicking, catching, or locking with inability to fully flex or extend the thumb depending on the severity. Symptoms may be worse in the morning and improve throughout the day. Diagnosis is made based on a thorough history and physical exam.

Studies have found that systemic conditions (e.g., dia betes mellitus, rheumatoid arthritis, hypothyroidism) and symptoms that have been present for at least 6 months are less likely to respond to nonoperative management⁶⁷. As with triggering in other digits, stepwise approach begins with nonsurgical management. This can include observation, avoiding inciting activities, NSAIDs, splinting, or CSI. The CSI demonstrated a success rate anywhere from 60-90% with the most benefit in the thumb⁶⁹. If there are ongoing symptoms after two injections, it is generally recommended to proceed with surgical release of the A1 pulley given risk of tendon degeneration and rupture with repeated injections⁷⁰. The FPL sheath of the thumb dif fers from the flexor tendon sheaths of the fingers. While the A1 pulley is present in the thumb, a cadaveric study found a high rate of the variable pulley (Av) at the thumb just distal to the A1 pulley. This structure should also be partially released if there is ongoing triggering after release of the A1 pulley, but care must be taken to avoid injury to the more distal oblique pulley due to the potential of bowstringing⁷¹.

When considering a thumb pain differential, it is worth mentioning Linburg-Comstock syndrome. This describes an anomalous tendinous slip or hypertrophic tenosy novium connection between the thumb FPL and the index flexor digitorum profundus (FDP) tendons, which can be acquired or congenital. Prior studies showed it can be unilateral (20-31%) or bilateral (7-14%)^66,72,73. This con nection can be either asymptomatic or symptomatic (also called thumb-index flexor tenosynovitis). In the symptom atic patient, the most frequent presentation is an insidious onset of vague, activity related pain to the thumb, thenar region, and radial wrist/forearm. Patients may complain of tightness or cramping, but the pathognomonic sign of Lindburg-Comstock syndrome is the lack of independent thumb and index flexion with thumb IP joint flexion⁷⁴. Hence, the most reliable provocative test is reproducible pain with passive extension of the index finger while flexing the IP joint of the thumb^66,74. Regarding imaging, MRI can aid in diagnosis and locating the anomalous connection for surgical planning⁷³. Unless symptomatic, no treatment is warranted. In the symptomatic patient, CSI of the FPL sheath aids in diagnosis and treatment. If pain persists despite CSI, open release of the anomalous connection provides significant relief^73,74.

Flexor Carpi Radialis (FCR) Tendonitis

The FCR muscle originates at the medial epicondyle and acts as a strong wrist flexor. The tendon is fixed in a volar tunnel radial to the carpal tunnel, courses distally over the volar aspect of the scaphoid, and finally enters a fibro-osseous tunnel adjacent to the trapezium with in sertion at the trapezium and second and third metacarpal bases⁷⁵. The FCR tendon occupies roughly 90% of the fibro-osseous tunnel which is predominantly formed by bone, leaving very little room for swelling⁷⁶. Throughout the anatomic course of the tendon, osseous ridging created by osteophytes of the scaphotrapezium articulation can encroach on the FCR tendon resulting in tendinopathy and partial or complete tear. This anatomic relationship explains the coexistence of FCR tendinopathy and STT arthritis⁷⁷.

FCR tendinopathy is associated with repetitive flexion of the wrist, fracture of the scaphoid, fracture of the distal radius, excision of a ganglion, or blunt trauma⁷⁸. Pain is typically located at the radial volar border of the wrist. It worsens with resisted wrist flexion and radial deviation, as well as with passive stretching of the FCR during hy perextension. Pain may also be present with extension of the second and third fingers⁷⁹. Imaging is not neces sary to diagnose FCR tendinopathy. Radiographs can be obtained to determine the presence of osteoarthritic changes. MRI, if obtained, can lead to incidental findings. A study demonstrated signal changes of the FCR tendon on MRI in about 1 in 30 patients, and 55% of these pa tients were without radial-sided wrist pain⁸⁰. In addition, the signal changes of the FCR tendon were associated with peritrapezial osteoarthritis⁸⁰.

Nonoperative treatment with rest, splint, NSAIDs, and possible CSI is first line treatment. Lidocaine injection into the FCR tendon sheath can be used for diagnostic purposes, although caution must be taken to avoid infiltra tion of the radial artery⁷⁹. Less than 10% of patients are reported to improve with conservative management. Surgi cal decompression of the FCR tunnel may be required if symptoms do not improve, especially when there is lack of evidence of post-traumatic or degenerative changes. Surgical release is achieved by opening the retinacular septum between the carpal tunnel and the FCR tunnel. Roughly 60% of patients achieved complete resolution of symptoms following surgical release of the septum⁷⁹. A ruptured FCR tendon does not usually need to be repaired, as there is typically minimal loss of function in the setting of an intact flexor carpi ulnaris (FCU) tendon.

Superficial radial nerve (SRN) impingement

SRN impingement, also known as Wartenberg Syndrome or Cheiralgia Paresthetica, should be considered when a patient presents with burning pain at the radial aspect of the wrist that radiates into the dorsum of the thumb. SRN impingement is a rare compression neuropathy⁸¹. Ana tomically, the radial nerve bifurcates into the SRN and the posterior interosseous nerve (PIN) at the proximal forearm. The SRN courses distally deep to the brachioradialis and exits roughly 9 cm proximal to the radial styloid⁸¹. As it courses superficially in the subcutaneous tissue between the tendons of brachioradialis and extensor carpi radialis longus (ECRL), it innervates the dorsum of the thumb, index, and radial half of the long finger. The greatest risk of compression occurs when the nerve transitions from the deep to superficial tissue, especially when the arm is pronated^81,82. SRN impingement may be related to tight wristwatches, lipomas, osteophytes, shoulder surgery positioning, and work-related activities with excessive pronation or supination^82,83.

Patients present with tingling, paresthesia, and burn ing pain over the dorsal aspect of the thumb. They tend to have symptoms at rest, as opposed to tendinopathy symptoms that occur during use. Abnormal touch percep tion, abnormal two-point discrimination, and aggravation of symptoms with forced forearm pronation and wrist ulnar deviation may all be found on physical exam⁸⁴. A positive Tinel’s sign may be elicited by lightly tapping over the distribution of the superficial branch of the radial nerve. There have been studies associating SPN impingement with diabetes⁸⁴. In addition, up to 50% of patients experi ence SRN compressive neuropathy with de Quervain’s⁸⁴. Radiographs or advanced imaging are not necessary for diagnosis and EMG demonstrates inconsistent results⁸⁴.

There is limited literature related to management. Spontaneous resolution is common, especially after removal of external compression. Rest, splinting, and NSAIDs are considered first-line treatment. Providers may consider a steroid injection, although little has been studied on outcomes in this regard. Dellon et al. demon strated that 37% of patients improved without surgical management, and 37% recovered with excellent results following surgery⁸⁴. More recently, there was a case report published on ultrasound-guided hydro-dissection by injecting 1% lidocaine around the nerve⁸⁵. They sug gested 90% pain relief but there was no discussion on length of time for relief of symptoms. Finally, there are no randomized controlled trials assessing the difference of treatment management.

Ganglion cyst

Ganglion cysts of the wrist and hand are common be nign lesions that can present either at the dorsal (more common) or volar aspect of the wrist. They are thought to form from mucin production by modified synovial cells or fibroblasts at the synovial capsular junction following tissue trauma. The material coalesces into an area of degeneration, and a cyst forms⁸⁶. The dorsal ganglion cysts most commonly arise from the SL interval, while the volar ganglions arise from the radioscaphoid or STT joint adjacent to the radial artery and FCR tendon⁸⁷. Smaller dorsal ganglions can be more symptomatic possibly due to a pressure phenomenon within the SLL⁸⁸. Patients may present with no history of injury and minimal physical exam findings except for tenderness to palpation overlying the SLL or pain with loaded wrist extension. On physical exam, the cyst is assessed for transillumination, mobility, and softness. Providers should confirm that a presumed volar cyst is not pulsatile, as a radial artery aneurysm can present in a similar location as a volar ganglion cyst⁸⁷. The pain of a dorsal cyst is postulated to be caused by com pression of the PIN since its fibers supply innervation to the dorsal wrist capsule, whereas the pain of a volar cyst is thought to be caused by median nerve compression^86,87.

A 1999 study evaluated 21 patients with vague dorsal wrist pain, in which 18 of them demonstrated a small ganglion upon surgical exploration that was confirmed by histology⁸⁹. MRIs have proven beneficial for the diagnosis of occult dorsal ganglions with very high signal intensity on T2-weighted images due to high water content. The advanced imaging can show an intimate relationship of the cyst with the SLL and can demonstrate the ganglion stalk deeply arising from the joint⁹⁰. While ultrasound has the same sensitivity and specificity as an MRI, it is more dependent on the operator⁸⁷. Patients can attempt non operative management via observation or aspiration, but surgical excision is recommended for continued pain or recurrence. Volar ganglion cysts have a higher recurrence rate following aspiration, and open excision results in lower recurrence. During open excision, the cyst and/or area of myxomatous degeneration should be circumferentially dissected down to the level of the stalk near the site of the cyst’s origin. The surgeon must take care to avoid injury to the SLL for dorsal ganglions and radial artery for volar ganglions⁸⁷. Arthroscopic cyst excision is an alternative option for surgical treatment but is used less commonly than open excision.